975 nm multimode semiconductor lasers with high-order Bragg diffraction gratings

The 975 nm multimode diode lasers with high-order surface Bragg diffraction gratings have been simulated and calculated using the 2D finite difference time domain (FDTD) algorithm and the scattering matrix method (SMM). The periods and etch depth of the grating parameters have been optimized. A board area laser diode (BA-LD) with high-order diffraction gratings has been designed and fabricated. At output powers up to 10.5 W, the measured spectral width of full width at half maximum (FWHM) is less than 0.5 nm. The results demonstrate that the designed high-order surface gratings can effectively narrow the spectral width of multimode semiconductor lasers at high output power.